Q waves in hypertrophic cardiomyopathy in relation to the distribution and severity of right and left ventricular hypertrophy

Patterns of Electrocardiographic Abnormalities in Children with Hypertrophic Cardiomyopathy

Hypertrophic cardiomyopathy (HCM), a common cardiomyopathy in children, is an important cause of morbidity and mortality. Early recognition and appropriate management are important. An electrocardiogram (ECG) is often used as a screening tool in children to detect heart disease. The ECG patterns in children with HCM are not well described.ECGs collected from an international cohort of children, and adolescents (≤ 21 years) with HCM were reviewed. 482 ECGs met inclusion criteria. Age ranged from 1 day to 21 years, median 13 years. Of the 482 ECGs, 57 (12%) were normal. The most common abnormalities noted were left ventricular hypertrophy (LVH) in 108/482 (22%) and biventricular hypertrophy (BVH) in 116/482 (24%) Of the patients with LVH/BVH (n = 224), 135 (60%) also had a strain pattern (LVH in 83, BVH in 52). Isolated strain pattern (in the absence of criteria for hypertrophy) was seen in 43/482 (9%). Isolated pathologic Q waves were seen in 71/482 (15%). Pediatric HCM, 88% have an abnormal ECG. The most common ECG abnormalities were LVH or BVH with or without strain. Strain pattern without hypertrophy and a pathologic Q wave were present in a significant proportion (24%) of patients. Thus, a significant number of children with HCM have ECG abnormalities that are not typical for "hypertrophy". The presence of the ECG abnormalities described above in a child should prompt further examination with an echocardiogram to rule out HCM.

Associations between electrocardiographic findings and echocardiographic profiles in patients with hypertrophic cardiomyopathy

BACKGROUND

The relationships between electrocardiography (ECG) findings and echocardiographic profiles in patients with hypertrophic cardiomyopathy (HCM) are not fully understood.

METHODS

One hundred forty patients (mean age: 62.9 ± 15.3 years, 96 men) with HCM were studied. We assessed the associations between ECG findings and echocardiographic findings including maximum left ventricular wall thickness, HCM subtypes and distribution of left ventricular hypertrophy (LVH): the LV was divided into basal, mid, and apical segments by dividing it into thirds along the long axis.

RESULTS

In ECG, LVH by voltage criteria, abnormal Q wave, negative T wave, and giant negative T wave (GNT) were observed in 74 (53 %), 30 (21 %), 132 (94 %), and 25 (18 %) of the patients, respectively. In two groups with and without an LVH pattern according to voltage criteria in ECG, there were no significant differences in maximum LV wall thickness, subtype of HCM, and distribution of LVH. Regarding an abnormal Q wave, the proportion of patients with LVH in the basal segment was significantly higher in patients with an abnormal Q wave than in patients without an abnormal Q wave (87 % vs 61 %, p = 0.008). An abnormal Q wave was not observed in patients with LVH confined to the apex. Patients with a GNT included patients with LVH located at only the apex (apical HCM), LVH from the mid segment to apex, and LVH from the base to apex. No GNT was found in patients with hypertrophy located in the upper region from the base to mid segment of the LV.

CONCLUSIONS

In patients with HCM, there was no significant correlation between the presence of LVH by voltage criteria in ECG and echocardiographic findings. An abnormal Q wave was associated with disproportionate hypertrophy of the basal wall and a GNT reflected the presence of LVH in the apical segment.

Electrocardiographic abnormalities in patients with cardiomyopathies

Abnormalities in impulse generation and transmission are among the first signs of cardiac remodeling in cardiomyopathies. Accordingly, 12-lead electrocardiogram (ECG) of patients with cardiomyopathies may show multiple abnormalities. Some findings are suggestive of specific disorders, such as the discrepancy between QRS voltages and left ventricular (LV) mass for cardiac amyloidosis or the inverted T waves in the right precordial leads for arrhythmogenic cardiomyopathy. Other findings are less sensitive and/or specific, but may orient toward a specific diagnosis in a patient with a specific phenotype, such as an increased LV wall thickness or a dilated LV. A "cardiomyopathy-oriented" mindset to ECG reading is important to detect the possible signs of an underlying cardiomyopathy and to interpret correctly the meaning of these alterations, which differs in patients with cardiomyopathies or other conditions.

Machine Learning Approaches in Diagnosis, Prognosis and Treatment Selection of Cardiac Amyloidosis

Cardiac amyloidosis is an uncommon restrictive cardiomyopathy featuring an unregulated amyloid protein deposition that impairs organic function. Early cardiac amyloidosis diagnosis is generally delayed by indistinguishable clinical findings of more frequent hypertrophic diseases. Furthermore, amyloidosis is divided into various groups, according to a generally accepted taxonomy, based on the proteins that make up the amyloid deposits; a careful differentiation between the various forms of amyloidosis is necessary to undertake an adequate therapeutic treatment. Thus, cardiac amyloidosis is thought to be underdiagnosed, which delays necessary therapeutic procedures, diminishing quality of life and impairing clinical prognosis. The diagnostic work-up for cardiac amyloidosis begins with the identification of clinical features, electrocardiographic and imaging findings suggestive or compatible with cardiac amyloidosis, and often requires the histological demonstration of amyloid deposition. One approach to overcome the difficulty of an early diagnosis is the use of automated diagnostic algorithms. Machine learning enables the automatic extraction of salient information from “raw data” without the need for pre-processing methods based on the a priori knowledge of the human operator. This review attempts to assess the various diagnostic approaches and artificial intelligence computational techniques in the detection of cardiac amyloidosis.

Multinational Federated Learning Approach to Train ECG and Echocardiogram Models for Hypertrophic Cardiomyopathy Detection

BACKGROUND

Novel targeted treatments increase the need for prompt hypertrophic cardiomyopathy (HCM) detection. However, its low prevalence (0.5%) and resemblance to common diseases present challenges that may benefit from automated machine learning-based approaches. We aimed to develop machine learning models to detect HCM and to differentiate it from other cardiac conditions using ECGs and echocardiograms, with robust generalizability across multiple cohorts.

METHODS

Single-institution HCM ECG models were trained and validated on external data. Multi-institution models for ECG and echocardiogram were trained on data from 3 academic medical centers in the United States and Japan using a federated learning approach, which enables training on distributed data without data sharing. Models were validated on held-out test sets for each institution and from a fourth academic medical center and were further evaluated for discrimination of HCM from aortic stenosis, hypertension, and cardiac amyloidosis. Last, automated detection was compared with manual interpretation by 3 cardiologists on a data set with a realistic HCM prevalence.

RESULTS

We identified 74 376 ECGs for 56 129 patients and 8392 echocardiograms for 6825 patients at the 4 academic medical centers. Although ECG models trained on data from each institution displayed excellent discrimination of HCM on internal test data (C statistics, 0.88-0.93), the generalizability was limited, most notably for a model trained in Japan and tested in the United States (C statistic, 0.79-0.82). When trained in a federated manner, discrimination of HCM was excellent across all institutions (C statistics, 0.90-0.96 and 0.90-0.96 for ECG and echocardiogram model, respectively), including for phenotypic subgroups. The models further discriminated HCM from hypertension, aortic stenosis, and cardiac amyloidosis (C statistics, 0.84, 0.83, and 0.88, respectively, for ECG and 0.93, 0.94, 0.85, respectively, for echocardiogram). Analysis of electrocardiography-echocardiography paired data from 11 823 patients from an external institution indicated a higher sensitivity of automated HCM detection at a given positive predictive value compared with cardiologists (0.98 versus 0.81 at a positive predictive value of 0.01 for ECG and 0.78 versus 0.59 at a positive predictive value of 0.24 for echocardiogram).

CONCLUSIONS

Federated learning improved the generalizability of models that use ECGs and echocardiograms to detect and differentiate HCM from other causes of hypertrophy compared with training within a single institution.

Deciphering hypertrophic cardiomyopathy with electrocardiography

The comprehensive assessment of patients with hypertrophic cardiomyopathy is a complex process, with each step concurrently focusing on confirmation of the diagnosis, differentiation between sarcomeric and non-sarcomeric disease (phenocopy), and prognostication. Novel modalities such as genetic testing and advanced imaging have allowed for substantial advancements in the understanding of this condition and facilitate patient management. However, their availability is at present not universal, and interpretation requires a high level of expertise. In this setting, electrocardiography, a fast and widely available method, still retains a significant role in everyday clinical assessment of this population. In our review, we follow a stepwise approach for the interpretation of each electrocardiographic segment, discussing clinical implications of electrocardiographic patterns in sarcomeric disease, their value in the differential diagnosis from phenocopies, and impact on patient management. Outlining the substantial amount of information to be obtained from a simple tracing, we exhibit how electrocardiography is likely to remain an integral diagnostic tool in the future as well.

Right ventricular involvement in hypertrophic cardiomyopathy: evidence and implications from current literature

Objectives. In current guidelines, hypertrophic cardiomyopathy (HCM) is defined by hypertrophy of the left ventricle (LV). Less attention has been given to the right ventricle (RV) in patients with HCM. We wanted to provide an overview of current literature on RV involvement in HCM. Design. We performed a systematic search in PubMed and added additional articles by manual screening of references. The quality of the articles was assessed according to the GRADE system. Results. We identified 35 original articles on RV involvement in HCM. Based on these publications, RV hypertrophy occurs in 28-44% of HCM patients, depending on the cut-off value for hypertrophy and the method for assessment. Histological studies show the same structural changes in RV as are typically described in the LV cardiomyocyte hypertrophy and disarray, as well as fibrosis. These changes are similar, but less pronounced in the RV than in the LV. We discuss how HCM can impact the RV, either through a primary involvement similar to the LV or secondary to hemodynamic effects resulting from LV dysfunction. RV dysfunction in HCM is associated with higher mortality, partly due to an increased risk of ventricular tachycardia and sudden cardiac death. Conclusions. The evidence for RV involvement in HCM is limited. Multimodal imaging assessment of the RV should be included in the work-up of patients with HCM, and the added value of including RV function in the risk stratification algorithm should be further explored.

Sex differences in cardiac magnetic resonance features in patients with hypertrophic cardiomyopathy

Whether sex differences exist in cardiac magnetic resonance (CMR) findings in patients with hypertrophic cardiomyopathy (HCM) remain unknown. We sought to assess and compare CMR characteristics in male and female patients with HCM. From January-2006 to October-2017, 165 consecutive HCM patients evaluated with CMR were included. All clinical and complementary test information was prospectively collected. At the time of CMR evaluation women were older (70 [57-75] vs. 61 [47-72] years, p = 0.02) and more symptomatic in terms of dyspnea (New York Heart Association class II-IV 47.2 vs. 24.1%, p = 0.003) and palpitations (19.6 vs. 4.6%, p = 0.006) and received more frequently treatment with diuretics (49.1% vs. 23.4%, p = 0.001). On echocardiographic examination more women had obstructive physiology (45.1 vs. 20.6%, p = 0.002). On CMR evaluation, women showed smaller left ventricular end-systolic volume index (13 [10-15] vs. 16 [13-21] ml/m², p < 0.001), higher left ventricular ejection fraction (77 [74-80] vs. 72 [66-78]%, p = 0.004), more marked left ventricular outflow tract acceleration (54.7 vs. 26.4%, p < 0.001) and mitral regurgitation (33.3 vs. 12.7%, p = 0.002). In multivariable analysis, female sex [OR 2.44 (1.04-5.73), p = 0.04] and left ventricular end-systolic volume index [OR 1.60 (1.08-2.38), p = 0.018] were independently associated with obstructive physiology. Women with HCM have more frequently obstructive physiology, a finding that could be related to the smaller left ventricular end-systolic volume.

Relationship between electrocardiographic findings and Cardiac Magnetic Resonance phenotypes in patients with Hypertrophic Cardiomyopathy

Background

Q waves and negative T waves are common electrocardiographic (ECG) abnormalities in patients with Hypertrophic Cardiomyopathy (HCM). Several studies correlated ECG findings with presence and extent of fibrosis and hypertrophy; however, their significance remains incompletely clarified. Our study aimed to explain the mechanism behind Q and negative T waves by comparing their positions on a 12-lead ECG with phenotypes observed at Late Gadolinium Enhancement (LGE) Cardiac Magnetic Resonance (CMR).

Methods

12-lead ECG and LGE-CMR were performed in 88 consecutive patients with HCM (42 SD 16 years, 65 males). Using Delta Thickness ratio (DT ratio), and “global” and “parietal” LGE at CMR, the extent and distribution of myocardial hypertrophy and fibrosis were studied in correlation with ECG abnormalities.

Results

Q waves in different leads were not associated with “parietal” LGE score. Lateral Q waves correlated with an increased DT ratio Inferior Septum/Lateral wall (p = 0.01). A similar correlation between inferior Q waves and an increased DT Ratio Anterior wall/Inferior wall was of borderline statistical significance (p = 0.06). As expected, ECG signs of LV hypertrophy related to a raised Left Ventricular Mass Index (LVMI) (p < 0.0001) and mean wall thickness (p = 0.01). Depolarization disturbances, including negative T waves in lateral (p = 0.044) and anterior (p = 0.031) leads correlated with “parietal” LGE scores while QT dispersion (p = 0.0001) was associated with “global” LGE score.

Conclusion

In HCM patients, Q waves are generated by asymmetric hypertrophy rather than by myocardial fibrosis, while negative T waves result from local LGE distribution at CMR.

The relationship between electrocardiographic changes and CMR features in asymptomatic or mildly symptomatic patients with hypertrophic cardiomyopathy

To investigate the relationship between electrocardiographic (ECG) abnormalities and left ventricular (LV) segmental hypertrophy and myocardial fibrosis assessed by cardiovascular magnetic resonance (CMR) in asymptomatic or mildly symptomatic patients with hypertrophic cardiomyopathy (HCM). 118 asymptomatic or mildly symptomatic patients with HCM were examined with late gadolinium enhancement (LGE) CMR, 12-lead ECG, and echocardiography. The distribution and magnitude of LV segmental hypertrophy and LGE were assessed and analyzed in relation to ECG abnormalities. Abnormal electrocardiograms were found in 113 of 118 (95%) patients. Negative T waves were associated with greater apical septal thickness (P = 0.009) and an increased ratio of LV septum to free wall thickness (P = 0.01). Giant negative T waves (GNT) were found in 19 patients (16%), and were associated with apical HCM (P < 0.001), greater apical thickness (P = 0.004), and increased ratio of LV apical to basal wall thickness (P < 0.001). However, no significant association was demonstrated between GNT and apical LGE (P = 0.71). Abnormal Q waves were associated with greater basal anteroseptal thickness (P = 0.001), maximal basal thickness (P = 0.004), and more segments with extensive LGE (>75% wall thickness involved) (P = 0.001). LV hypertrophy was related to greater LV mass (P = 0.002) and LV end diastolic volume (P = 0.002). In addition, a modest but significant correlation was observed between maximum LV wall thickness and the Romhilt-Estes score (r = 0.41, P < 0.001). GNT were associated with apical HCM and an increased ratio of LV apical to basal wall thickness. Abnormal Q waves were related to basal anteroseptal hypertrophy and segmental extensive LGE.

ECG characteristics according to the presence of late gadolinium enhancement on cardiac MRI in hypertrophic cardiomyopathy

BACKGROUND

Late gadolinium enhancement (LGE) on cardiac MRI (CMR) has been described as an independent predictive factor of cardiovascular events among patients with hypertrophic cardiomyopathy (HCM). LGE and Q waves are considered as myocardial scar markers but their relation in the context of HCM is poorly established and has to be more supported. The objective of the study was to compare ECG findings in the presence or absence of LGE.

METHODS

42 patients with HCM confirmed by CMR were included in the study. ECG abnormalities including abnormal Q waves and five ECG scores of left ventricular hypertrophy were assessed and compared according to LGE presence and its extension. Some CMR features, such as septal to posterior wall thickness ratio, were also studied according to the presence of LGE and the presence of abnormal Q waves.

RESULTS

Abnormal Q waves were more prevalent in the LGE (+) group (60% vs 12%; p=0.002), but there was no correlation between location of Q waves on ECG and territory of LGE on CMR. Among patients with LGE, quantitative analysis of LGE was not different in the presence or absence of Q waves. In contrast to the LGE mass, septal to posterior wall thickness was higher in patients with abnormal Q waves (2.3±0.7 vs 1.6±0.5; p=0.012).

CONCLUSIONS

Although abnormal Q waves were more prevalent in the presence of LGE, no correlation was found with the LGE location and extent. These data suggest that abnormal electrical activation of the hypertrophied ventricular septum represented by a high septal to posterior wall thickness ratio seems to be an important mechanism of abnormal Q waves in HCM.

Risk markers of sudden cardiac death in standard 12-lead electrocardiograms

The annual incidence of sudden cardiac death (SCD) is estimated at 1 per 1,000 for adults over the age of 35 years, and 1 per 100,000 for adolescents and young adults. Although the overall incidence of unexpected SCD among previously healthy persons is small, the emotional impact of these events is devastating. The 12-lead electrocardiogram (ECG) has been used as a risk assessment tool from healthy occupational applicants and athletes to patients with cardiovascular disorders. The ECG is also routinely recorded in the majority of patients hospitalized for non-cardiovascular causes. Thus, it is a widely used tool intended for identification of unsuspected heart disease generally, as well as for diagnosing specific disorders predisposing to fatal arrhythmias in subjects who have not experienced such events but who are at increased risk. Recognition of specific ECG features is of importance for prevention of SCD in asymptomatic persons. The purpose of this review is to catalog the disorders associated with SCD that may be reflected in 12-lead ECGs seen in office or hospital practices and to discuss their prevalence and the magnitude of risks. The focus is on ECG findings suggesting increased SCD risk among the asymptomatic subjects without previously diagnosed cardiac disease.

Correlation of electrocardiographic changes and myocardial fibrosis in patients with hypertrophic cardiomyopathy detected by cardiac magnetic resonance imaging

BACKGROUND

Despite several electrophysiologic and pathologic studies, the cause of electrocardiographic (ECG) changes in patients with hypertrophic cardiomyopathy (HCM) remains unclear. Late gadolinium enhancement (LGE) cardiovascular magnetic resonance (CMR) imaging can detect myocardial fibrosis. We aimed to assess the relationship between ECG findings and LGE in such patients.

HYPOTHESIS

Myocardial LGE may be associated with ECG changes in HCM.

METHODS

Seventy consecutive patients with HCM (mean age, 55.5 ± 10.7 years; 47 males) underwent CMR and 12-lead ECG. The subjects were divided into 3 groups according to the type of hypertrophy: the asymmetric septal hypertrophy group (ASH group, n = 31), the apical hypertrophy group (AP group, n = 22), and concentric hypertrophy group (CH group, n = 17). The transmural and segmental extent, pattern, and location of myocardial LGE were assessed and analyzed in relation to ECG changes.

RESULTS

All of the subjects showed some degree of LGE on CMR. The AP group showed significantly higher prevalence of negative T-wave (P = 0.028) and deep negative T-wave inversion (P = 0.001) than the ASH and CH groups. The total volume of LGE did not show any significant association with ECG changes. LGE detected at the interventricular septum was associated with increased QRS duration (P = 0.009) and was found in 94% of the ASH group, 59% of the AP group, and 77% of the CH group. LGE at the apex of the heart was present in 32% of the ASH group, 73% of the AP group, and 35% of the CH group and was also associated with negative T-wave (P = 0.006) and deep negative T-wave inversion (P = 0.018). Multifocal LGE lesions were associated with increased QRS duration (P = 0.039) as opposed to single nodular or patchy pattern of presence.

CONCLUSIONS

The location of myocardial LGE in HCM shows significant association with various ECG changes. This may be useful information for initially evaluating subjects with HCM and adds pathophysiological insight into understanding ECG changes in myocardial diseases that cannot be explained otherwise.

Insights and challenges in hypertrophic cardiomyopathy, 2012

We present a contemporary overview of hypertrophic cardiomyopathy (HCM), incorporating recent thinking on disease mechanisms and advances in therapy. Clinical, pathological, genetic, and mechanistic definitions of HCM are discussed. The genetic profile of HCM in both adults and children is explored to the extent of present knowledge. The spectrum of morphological and histological abnormalities in HCM is reviewed, including involvement of the right ventricle, which is less widely recognised. Morbidity and mortality from HCM may result from diastolic dysfunction, ischaemia, left ventricular outflow tract obstruction, mitral regurgitation, supraventricular and ventricular arrhythmia, or--less commonly--progression to "burnt out" disease or sudden cardiac death (SCD). Defibrillators offer an efficacious means of averting SCD, but are not without their complications, underscoring the importance of identifying at-risk cases. We address the strengths and weaknesses of prognostication based on readily obtainable clinical markers, and discuss the integration of auxiliary approaches such as genotyping, cardiovascular magnetic resonance, and fractionation analysis into existing risk stratification guidelines. Finally, we provide an update on the pharmacological and interventional management of HCM, including the advent of disease-modifying therapy.

A cardiac pseudo-tumor associated with pseudo-infarction electrocardiographic pattern

The electrocardiographic presentation of Q waves is an important diagnostic indication of myocardial infarction and other differential diagnoses. We report a case in which the electrocardiography revealed significant Q waves in V1 to V4. In addition, echocardiography disclosed an encapsulated mass lesion over the interventricular septum. Rather than confirm a cardiac tumor, magnetic resonance imaging disclosed hypertrophy of the myocardium with the ventricular septum showing prominent thickness > 3 cm. Hypertrophic cardiomyopathy was diagnosed. Cardiac pseudo-tumor with a pseudo-infarction electrocardiography pattern can be a rare presentation of hypertrophic cardiomyopathy.

Association of myocardial fibrosis, electrocardiography and ventricular tachyarrhythmia in hypertrophic cardiomyopathy: a delayed contrast enhanced MRI study

BACKGROUND

Patients with hypertrophic cardiomyopathy (HCM) are predisposed to ventricular tachyarrhythmia (VT); likely due to myocardial fibrosis or disarray. Delayed hyperenhancement magnetic resonance imaging (DHE-MRI) accurately detects myocardial fibrosis (scar). We sought to determine the association between septal thickness, myocardial scar and VT.

METHODS

Sixty-eight patients (mean age 44 years, 69% males) with documented HCM underwent cine MRI (Siemens Sonata or Avanto 1.5 T scanner, Erlangen, Germany) in short axis, 2, 3 and 4-chamber views and maximal interventricular septal thickness was recorded at end-diastole. Corresponding DHE-MR images (8-10 mm thick) were obtained, approximately 20 min after injection of 0.2 mmol/kg of Gadolinium. Scar was determined semi-automatically (as % of total myocardium) using VPT software (Siemens) and defined as intensity >2 SD above viable myocardium in a 12 segment short-axis model at apex, mid LV and base. Presence of VT (documented on ambulatory ECG monitoring) and history of sudden death were recorded.

RESULTS

One patient had a history of sudden death and 9 (13%) had VT on ambulatory ECG monitoring. On DHE-MRI, 39 (57%) patients had myocardial scar. Patients with VT had significantly higher scar %, compared to those without: 14% [6, 19] vs. 6% [0, 10], P = 0.01. On logistic regression, only the size of the scar was a significant predictor of VT (P = 0.03).

CONCLUSIONS

HCM subjects with VT have a higher % of myocardial scarring noted on DHE-MRI, independent of septal thickness or beta-blocker use.

Cardiac magnetic field map topology quantified by Kullback-Leibler entropy identifies patients with hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is a common primary inherited cardiac muscle disorder, defined clinically by the presence of unexplained left ventricular hypertrophy. The detection of affected patients remains challenging. Genetic testing is limited because only in 50%-60% of all HCM diagnoses an underlying mutation can be found. Furthermore, the disease has a varied clinical course and outcome, with many patients having little or no discernible cardiovascular symptoms, whereas others develop profound exercise limitation and recurrent arrhythmias or sudden cardiac death. Therefore prospective screening of HCM family members is strongly recommended. According to the current guidelines this includes serial echocardiographic and electrocardiographic examinations. In this study we investigated the capability of cardiac magnetic field mapping (CMFM) to detect patients suffering from HCM. We introduce for the first time a combined diagnostic approach based on map topology quantification using Kullback-Leibler (KL) entropy and regional magnetic field strength parameters. The cardiac magnetic field was recorded over the anterior chest wall using a multichannel-LT-SQUID system. CMFM was calculated based on a regular 36 point grid. We analyzed CMFM in patients with confirmed diagnosis of HCM (HCM, n=33, 43.8+/-13 years, 13 women, 20 men), a control group of healthy subjects (NORMAL, n=57, 39.6+/-8.9 years; 22 women and 35 men), and patients with confirmed cardiac hypertrophy due to arterial hypertension (HYP, n=42, 49.7+/-7.9 years, 15 women and 27 men). A subgroup analysis was performed between HCM patients suffering from the obstructive (HOCM, n=19) and nonobstructive (HNCM, n=14) form of the disease. KL entropy based map topology quantification alone identified HCM patients with a sensitivity of 78.8% and specificity of 86.9% (overall classification rate 84.8%). The combination of the KL parameters with a regional field strength parameter improved the overall classification rate to 87.9% (sensitivity: 84.8%, specificity: 88.9%, area under ROC curve: 0.94). KL measures applied to discriminate between HOCM and HNCM patients showed a correct classification of 78.8%. The combination of one KL and one regional parameter again improved the overall classification rate to 97%. A preliminary prospective analysis in two HCM families showed the feasibility of this diagnostic approach with a correct diagnosis of all 22 screened family members (1 HOCM, 4 HNCM, 17 normal). In conclusion, Cardiac Magnetic Field Mapping including KL entropy based topology quantifications is a suitable tool for HCM screening.

Focalized Contractile Impairment at Hypertrophied Myocardium Proven in Consideration of Wall Stress in Patients With Hypertrophic Cardiomyopathy

In hypertrophic cardiomyopathy (HCM) a hyperkinetic state is sometimes observed in spite of impaired systolic function in the hypertrophied myocardium. The aim of the present study was to determine the mechanism of this paradox. Seventeen patients with HCM and 10 normal subjects underwent cine magnetic resonance (MR) imaging to measure percent systolic wall thickening and percent fractional shortening. The ratio of systolic radial wall stress of the LV at the hypertrophied myocardium over that at the nonhypertrophied myocardium was evaluated to describe the focal advantageous condition for wall thickening. The ratio was 0.66 +/- 0.36 at the start of contraction and 0.78 +/- 0.31 at early-systole, indicating consistently smaller radial wall stress at the hypertrophied myocardium. Although the condition for contraction was favorable (a ratio less than 1.00), percent systolic wall thickening at the hypertrophied myocardium (23.0 +/- 11.8%) was smaller than that at the nonhypertrophied myocardium (70.5 +/- 32.3%). Smaller end-diastolic dimension (HCM group; 45.2 +/- 4.2 mm, reference group; 48.9 +/- 4.1 mm, P = 0.04) with a statistically identical value of systolic decrease in intraventricular dimension (HCM group; 19.7 +/- 3.9 mm, reference group; 18.9 +/- 3.2 mm, P = 0.60) yielded high percent fractional shortening in patients with HCM (43.5 +/- 7.6%). Although contractile impairment was proven at the hypertrophied region with low radial wall stress in the HCM group, the smaller end-diastolic dimension in this group resulted in high percent fractional shortening.

Mechanisms of abnormal Q waves in hypertrophic cardiomyopathy assessed by intracoronary electrocardiography

INTRODUCTION

To clarify the mechanisms of abnormal Q waves in hypertrophic cardiomyopathy (HCM), local epicardial electrical activities were assessed by intracoronary electrocardiography (ECG).

METHODS AND RESULTS

Unipolar intracoronary ECG was recorded by introducing a guide wire for angioplasty into the left anterior descending artery (LAD) in 20 patients with HCM and 10 control subjects. Intracoronary ECG showed no Q waves in any control subjects. Intracoronary ECG showed no Q waves in 8 HCM patients without abnormal Q waves on surface ECG. In 12 HCM patients with abnormal Q waves on surface ECG, 4 showed Q waves on intracoronary ECG associated with regional wall-motion abnormalities, suggesting Q waves are formed by loss of electrical forces due to transmural myocardial fibrosis. The remaining 8 patients, who did not have Q waves on intracoronary ECG, showed greater thickening of the basal free wall than the apical free wall, with no wall-motion abnormalities. Intracoronary ECG was characterized by increased R or R' waves and prolonged R peak times at the proximal LAD, suggesting Q waves are formed by increased electrical forces of hypertrophied basal septal and/or ventricular free wall, unopposed by apical forces.

CONCLUSION

The study findings provide evidence for two mechanisms of abnormal Q waves in HCM: (1) loss of electrical forces due to transmural myocardial fibrosis, and (2) altered direction of resultant initial QRS vector due to increased electrical forces of disproportionate hypertrophy of the basal septal and/or ventricular free wall, unopposed by apical forces.

Hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy is a common genetically transmitted disease, defined clinically by the presence of unexplained left ventricular hypertrophy. The disease has a varied clinical course and outcome; many patients have little or no discernible cardiovascular symptoms, whereas others have profound exercise limitation and recurrent arrhythmias. The overall risk of disease-related complications such as sudden death, endstage heart failure, and fatal stroke is roughly 1-2% per year, but the absolute risk in individuals varies as a function of underlying genetic abnormality, age, myocardial pathology, and other pathophysiological abnormalities such as impaired peripheral vascular responses. Genetic counselling and clinical risk stratification are relevant to all patients, but many therapeutic interventions, including septal alcohol ablation, septal myectomy, and implantable cardioverter defibrillators, are appropriate only in particular patient subsets. We review the management of patients with unexplained myocardial hypertrophy, considering the influence of underlying genetic and pathophysiological substrates on clinical decision-making.

Chronologic electrocardiographic changes in patients with hypertrophic cardiomyopathy associated with cardiac troponin 1 mutation

BACKGROUND

Deletion of lysine 183 (K183del) in the cardiac troponin I (cTnI) gene is one of the mutations that causes hypertrophic cardiomyopathy (HCM). However, the phenotypic expression of this mutation has not been well established.

METHODS AND RESULTS

We analyzed 10 probands with HCM associated with a K183del in the cTnI gene, as well as their family members. Forty-seven of these 80 subjects were found to be carriers and 33 were noncarriers. In the carrier subjects, electrocardiogram (ECG) abnormalities were initially noted during the early teenage years preceding echocardiographic abnormalities. Abnormal Q waves were found first and most frequently compared with other ECG abnormalities. Abnormal Q waves were frequently observed in leads II, III, aVF, V5, and V6 in teenage patients, whereas they were observed in many leads in patients >20 years old. The youngest of the 11 patients who had sudden cardiac death among studied pedigrees was a 14-year-old boy.

CONCLUSIONS

These results suggest that the first phenotypic manifestation in patients with HCM associated with a K183del mutation in the cTnI gene is abnormal Q waves in leads II, III, aVF, V5, and V6 during the early teenage years. To prevent sudden death in family members of patients with this mutation, it may be necessary to genetically diagnose it before age 10 years and to pay careful attention to any development of abnormal Q waves.

[Myocardial perfusion SPECT and isotopic ventriculography in obstructive and non-obstructive hypertrophic myocardiopathy]

OBJECTIVE

To evaluate the role of myocardial perfusion SPET and radionuclide ventriculography in patients with hypertrophic cardiomyopathy (HC).

METHODS

Exercise myocardial perfusion SPET with 99mTc-tetrofosmin and radionuclide ventriculography were performed in a consecutive series of 101 patients (54 15 years, 50 women, 55 with dynamic obstruction) diagnosed of HC by echo. Follow-up from the diagnosis was 9,9 6,7 years (1 to 28 years).

RESULTS

Thirty six percent of patients had perfusion defects (non reversible in 15 and reversible in 21). In non obstructive HC higher number of patients with non reversible defects (p = 0.01 was obseved and in patients with no reversible defects higher incidence of pathologic Q waves in ECG (p = 0.01), Higher ventricular volumes (p < 0.05), lower ejection fraction (p = 0,0001) and longer time to peak emptying velocity (p < 0.05). There were 4 cardiac deaths, 15 syncopes, 18 pacemakers and 6 myectomy. Ejection fraction was higher in patients with syncope (p = 0,034) and there was no isotopic variable predictive of mortality, pacemaker or myectomy.

CONCLUSIONS

Neither SPET nor radionuclide ventriculography have a prognostic role in patients with HC, but patients with syncope have higher values of ejection fraction. Patients with non reversible defects have higher rate of pathologic Q waves in ECG, higher ventricular volumes and lower ejection fraction. This is indicative of evolution to dilated form of HC.

Post partum creatine phosphokinase and its muscle-brain isoenzyme elevation and transient Q-wave in a patient with idiopathic hypertrophic subaortic stenosis

A primigravida with idiopathic hypertrophic subaortic stenosis, New York Heart Association Classification III, developed acute chest pain with significant ST segment depression together with a new Q-wave in chest lead V6 on the electrocardiograph following delivery under lumbar epidural analgesia. An intrapartum myocardial infarct was suspected because serial creatine phosphokinase and its muscle-brain isoenzyme levels were elevated in the postpartum period. However, the ST segment and the Q-wave changes returned to baseline within 4 h, thus eliminating the possibility of acute myocardial infarction. The uterus and placenta release creatine phosphokinase and its muscle-brain isoenzyme substantially during normal vaginal delivery, thus mimicking acute myocardial infarction. Consequently, the elevations of creatine phosphokinase and its muscle-brain fraction alone are not diagnostic of myocardial infarction in the postpartum period. The diagnosis of myocardial infarction must be based on the clinical picture, serial electrocardiogram recording and determination of lactate dehydrogenase and aspartate amino transferase.

Accuracy of surface electrocardiograms for differentiating children with hypertrophic cardiomyopathy from normal children

Most patients with hypertrophic cardiomyopathy have abnormal electrocardiograms. In this study of 37 matched pairs in the pediatric age group, the 12-lead electrocardiogram did not differentiate between affected and normal children reliably enough to allow it to be used as a screening test in the general population.

Relationship between electrocardiographic features and distribution of hypertrophy in patients with hypertrophic cardiomyopathy

To evaluate the relationship between the distribution of hypertrophy and the electrocardiographic findings in patients with hypertrophic cardiomyopathy (HCM), 54 HCM patients were studied using magnetic resonance imaging. The patients were divided into 4 groups according to hypertrophic patterns: (i) hypertrophy only at the apex (group I, n=12); (ii) hypertrophy in both the apex and base (group II, n=20); (iii) hypertrophy only at the base with asymmetric septal hypertrophy (ASH) (group IIIa, n=17); and (iv) hypertrophy only at the base without ASH (group IIIb, n=5). Abnormal Q waves in leads II, III and aVF were found in 1/12, 3/20, 10/17 and 0/5, respectively, and in leads I and aVL they were found in 1/12, 8/20, 4/17 and 1/5, respectively. The largest negative T waves (mm) were found in group I (group I vs group II vs group IIIa vs group IIIb: 15.2+/-5.3, 8.2+/-6.1, 1.6+/-2.0, 0.8+/-1.3, respectively). The largest positive T waves (mm) were identified in group IIIb (3.8+/-3.0, 6.8+/-3.2, 5.8+/-3.6, 9.3+/-2.1, respectively). The presence of abnormal Q waves reflected regional hypertrophy in HCM patients but the configuration of T waves represented the difference in the localization of hypertrophy between the basal and apical segments.

Outer limits of the athlete's heart, the effect of gender, and relevance to the differential diagnosis with primary cardiac diseases

Two concepts from pathologic descriptions of myocardial hypertrophy in trained individuals merit consideration: (1) The heart of the trained athlete can be twice the normal size, but histologic structure remains intact, and (2) the weight of the trained heart does not usually surpass the limit of 500 g, defined as the critical heart weight. Even though this threshold cannot be accepted dogmatically, the concept of an upper limit for physiologic cardiac remodeling is nevertheless relevant to the clinical question of distinguishing extreme expressions of athlete's heart from primary pathologic conditions. This morphologic distinction depends on whether the magnitude of cardiac remodeling in athletes exceeds that expected as a result of athletic conditioning alone. There has also been a great interest in understanding the impact that types of athletic conditioning and gender have on defining the upper limits to which such physiologic hypertrophy may extend.

New diagnostic options in hypertrophic cardiomyopathy

The pathophysiologic features and clinical manifestations of HCM have been elucidated by the introduction of several new diagnostic options. Knowledge of the molecular defects of HCM has advanced rapidly, and genetic screening studies have reemphasized the value of the standard electrocardiogram as an initial screening tool. Analysis of heart rate variability, late potentials, and QT dispersion were not found to be reliable prognostic markers in HCM. However, measurement of dispersion of conduction is probably a sensitive technique in identifying a high risk for sudden cardiac death. Significant developments include transthoracic and transesophageal echocardiography and their role in studying the mitral valve, early detection of left ventricular chamber dilatation, analysis of coronary flow, and intraoperative echocardiography. Finally, advances in the application of magnetic resonance imaging and positron-emission tomography are underway.